minor #18695 [DependencyInjection] Suggest ExpressionLanguage in composer.json (chalasr)

This PR was merged into the 2.7 branch.

Discussion
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[DependencyInjection] Suggest ExpressionLanguage in composer.json

| Q             | A
| ------------- | ---
| Branch?       | 2.7
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | n/a
| License       | MIT
| Doc PR        | n/a

As the DependencyInjection component has lots of classes containing uses of the ExpressionLanguage component, I propose to add it to the composer.json suggests.

Commits
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d6c9073 [DependencyInjection] Suggest ExpressionLanguage in composer.json

Author: fabpot

composer.json

@@ -29,6 +29,7 @@
     "suggest": {
         "symfony/yaml": "",
         "symfony/config": "",
+        "symfony/expression-language": "For using expressions in service container configuration",
         "symfony/proxy-manager-bridge": "Generate service proxies to lazy load them"
     },
     "autoload": {